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#1 crackedatom

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Posted 21 November 2006 - 10:08 AM

I was thinking of setting up (or at least learning a bit about) a RAID 0.
I'm reading the wiki about them right now, in the mean time does anyone have some pointers?

#2 Venom

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Posted 21 November 2006 - 10:12 AM

I was thinking of setting up (or at least learning a bit about) a RAID 0.
I'm reading the wiki about them right now, in the mean time does anyone have some pointers?


What will you be using it for?

#3 crackedatom

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Posted 21 November 2006 - 10:16 AM


I was thinking of setting up (or at least learning a bit about) a RAID 0.
I'm reading the wiki about them right now, in the mean time does anyone have some pointers?


What will you be using it for?

I have a few Maxtor harddrives, and I want to learn something new.
After a bit of reading, maybe something like the JBOD is better, the disks vary in size form 40gb to 80gb

#4 Venom

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Posted 21 November 2006 - 10:24 AM



I was thinking of setting up (or at least learning a bit about) a RAID 0.
I'm reading the wiki about them right now, in the mean time does anyone have some pointers?


What will you be using it for?

I have a few Maxtor harddrives, and I want to learn something new.
After a bit of reading, maybe something like the JBOD is better, the disks vary in size form 40gb to 80gb


Probably would be; RAID doesn't do well with different sized hard drives, at least not in my experience. Of course, that could be because of a bad configuration - so if I'm wrong feel free to correct.

#5 Booter

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Posted 21 November 2006 - 10:38 AM

The only really bad thing with JBOD is that once one drive fills and it jumps to the next; what if your going through a large download of something and it splits to the next drive. Say one of those fail, is that file/program screwed or does JBOD see if there is enough left on the first disk before jumping? I've never set up a JBOD before so I'm not entirely sure.

#6 Venom

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Posted 21 November 2006 - 11:59 AM

The only really bad thing with JBOD is that once one drive fills and it jumps to the next; what if your going through a large download of something and it splits to the next drive. Say one of those fail, is that file/program screwed or does JBOD see if there is enough left on the first disk before jumping? I've never set up a JBOD before so I'm not entirely sure.


Having used it only once, and just to link a bunch of small hdd's (6 gb and a 2 gb and a 8.2 gb), I honestly couldn't tell you since I didn't use it to download large files.

I got this off of pc-guide about JBOD :

It provides no fault tolerance, nor does it provide any improvements in performance compared to the independent use of its constituent drives. (In fact, it arguably hurts performance, by making it more difficult to use the underlying drives concurrently, or to optimize different drives for different uses.)


Edited by Venom, 21 November 2006 - 12:07 PM.


#7 crackedatom

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Posted 21 November 2006 - 12:29 PM

The only really bad thing with JBOD is that once one drive fills and it jumps to the next; what if your going through a large download of something and it splits to the next drive. Say one of those fail, is that file/program screwed or does JBOD see if there is enough left on the first disk before jumping? I've never set up a JBOD before so I'm not entirely sure.

Say a drive in a RAID 0 fails.
You lose everything.

#8 systems_glitch

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Posted 21 November 2006 - 12:32 PM

If I'm not completely off on this, and RAID 0 is striping, it will use each member in the array only to the capacity of the smallest member of the array. So, if you have three 80 GB drives and one 40 GB drive, the array will be only 160 GB (4 x 40 GB) There's no fault tolerance with RAID 0 either, and if one disk dies, /all/ data is gone, as the data is spread over the drives -- say you download one large file: parts of it will be written to all four drives at the same time (this is why RAID 0 is much faster than a single large drive, it writes in parallel to all drives). Then, if a disk breaks, that section of the file will be gone, making it pretty much impossible to cover it.

As mentioned, JBOD just fills the drives from start to finish as if they were all one really large drive. If one drive dies, the data on the others will still be accessable, although if a file is split between two drives, it will be partially lost. JBOD will take any drives, so if you have the aforementioned theoretical setup, the capacity would be 280 GB (3 x 80 GB + 1 x 40 GB).

If you want fault tolerance, you need RAID 1, which is mirroring. This is best used with drives of the same size, because as with RAID 0, the member of the smallest capacity will be the standard. In RAID 1, two drives are written in parallel with the /same/ data, so there is an exact duplicate made (this is why the drives need to be of the same size).

You can use RAID 0 + 1, in which you can RAID 0 two sets of two disks together (say, four 80 GB disks for two 160 GB RAID disks) and then RAID 1 those two together for redundancy (you would appear to have one 160 GB disk, but it would be fully backed up). This is usually considered the best method, as it's faster and much safer than just one very large disk. If you have an extra IDE controller, or a SATA/SCSI card (you can get SATA >> IDE converters, of course), you can add more than four disks to the system. Firewire/USB 2.0 is an option too, at least in software.

Remember that if you're using IDE drives, and you want your array to be fast, only use the mater channel on each array. Writing to two drives on the same bus wires slows things down a lot.

#9 Booter

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Posted 21 November 2006 - 12:46 PM


The only really bad thing with JBOD is that once one drive fills and it jumps to the next; what if your going through a large download of something and it splits to the next drive. Say one of those fail, is that file/program screwed or does JBOD see if there is enough left on the first disk before jumping? I've never set up a JBOD before so I'm not entirely sure.

Say a drive in a RAID 0 fails.
You lose everything.


I realize that but I was wondering that say 1/4 of your download is on /dev/hda and the other 3/4 is on /dev/hdb. I'm assuming that if either drive fails then the program/file is fucked. However, does the RAID recognize that the program/file you are trying to dl is 1GB, but you have 250MB left on /dev/hda and a bunch of room on /dev/hdb? Does it skip to /dev/hdb or does it still split it? I think it still splits, but was unsure.

#10 crackedatom

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Posted 21 November 2006 - 12:54 PM



The only really bad thing with JBOD is that once one drive fills and it jumps to the next; what if your going through a large download of something and it splits to the next drive. Say one of those fail, is that file/program screwed or does JBOD see if there is enough left on the first disk before jumping? I've never set up a JBOD before so I'm not entirely sure.

Say a drive in a RAID 0 fails.
You lose everything.


I realize that but I was wondering that say 1/4 of your download is on /dev/hda and the other 3/4 is on /dev/hdb. I'm assuming that if either drive fails then the program/file is fucked. However, does the RAID recognize that the program/file you are trying to dl is 1GB, but you have 250MB left on /dev/hda and a bunch of room on /dev/hdb. Does it skip to /dev/hdb or does it still split it. I think it still splits, but was unsure.

From what I've read, it just splits it since it sees everything as on disk.
but then say you delete something..then does the disk become fragmented like a regular hdd because it's forced to split files to fill the gaps.

Oh, and does anyone know of some *good* tutorials on setting up various configs?
I'm googleing at the moment, but that doesn't mean I'll find a great one <_<




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